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Impairment of masticatory function in hemiplegia
G Cruccu1, M Fornarelli, M Manfredi
1Department of Neurosciences, University of Rome La Sapienza, Italy.
Neurology
|February 1, 1988
Summary
Hemiplegic patients show reduced voluntary masseter muscle activity and altered jaw reflexes on the affected side. This suggests the opposite brain hemisphere significantly controls chewing movements and related reflexes.
Area of Science:
- Neurology
- Motor Control
- Neuroscience
Background:
- Hemiplegia, resulting from stroke, often affects motor function.
- The masseter muscle, crucial for mastication, is innervated bilaterally.
- Understanding hemispheric control over masticatory reflexes is important for rehabilitation.
Purpose of the Study:
- To investigate masseter muscle function in hemiplegic patients.
- To evaluate the influence of the contralateral hemisphere on masticatory reflexes.
Main Methods:
- Studied 15 hemiplegic patients.
- Assessed masseter muscle responses to nerve stimulation.
- Analyzed voluntary jaw activity and jaw jerk reflexes.
- Measured masseter silent periods during mastication.
Main Results:
- Normal direct motor responses to masseteric nerve stimulation.
- Reduced voluntary masseter activity on the paretic side.
- Jaw jerk was symmetric, but facilitation occurred only on the nonparetic side.
- Masseter silent periods were prolonged and ill-defined on the paretic side.
- Second silent period showed reduced size and increased habituation on the paretic side.
Conclusions:
- The contralateral hemisphere exerts dominant control over voluntary masseter activity.
- Multisynaptic masticatory reflexes are significantly influenced by the non-affected hemisphere.
- Findings highlight the role of hemispheric dominance in controlling complex motor functions like chewing.